1. Field of the Invention
This invention relates to apparatus for securing a transformer or choke core to a printed wiring board (PWB) and to the core mounting assembly itself.
2. Background Information
Voltage regulators and other electrical circuits for computers and the like often have integrated transformers, chokes and other inductive elements on the PWB. These elements usually consist of xe2x80x9cwindingsxe2x80x9d in the form of conductive paths printed or laid down on the PWB and a ferromagnetic core, usually of ferrite, mounted to the PWB. Optimum performance requires that the core be maintained close to the windings on the PWB.
Typically the ferromagnetic cores with which we are concerned consist of two mirror image core sections which are positioned on opposite sides of the PWB and are brought together through appropriately shaped through holes in the PWB so that one or both of the core sections is positioned close to the windings on the board. Currently that assembly is done by hand. The assembler must hold the two core sections together from opposite sides of the PWB while applying tape or glue to those parts. The assembler must then press one core section against a side of the board carrying the winding while applying adhesive to hold the core sections in the correct position. Usually, the adhesive is an epoxy material which takes time to cure. Therefore, the assembler must hold the parts together for several minutes to be sure that the adhesive has set completely. This obviously decreases the throughput of the manufacturing line for the voltage regulators and other circuits on printed wiring boards having such integral cores. Also, the assembler does not always hold the core sections together in the same way from board to board while the adhesive sets. Resultantly, the gap between the two core sections is not consistent from unit to unit which adversely affects the electrical performance of the circuit on the PWB and lowers the overall product yield.
The prior assemblies are disadvantaged also because the adhered core section cannot be separated in the event repair or replacement becomes necessary. Also, the adhesive or glue can separate over time resulting in circuit failure.
Accordingly it is an object of the present invention to provide an improved transformer or choke core mounting assembly. Another object of the invention is to provide an assembly of this type which is relatively easy to implement.
A further object of the invention is to provide such an assembly which results in consistent performance from unit to unit.
A further object of the invention is to provide an improved clamp assembly for mounting a transformer or choke core to a printed wiring board.
Another object of the invention is to provide such a clamp assembly which is relatively easy and inexpensive to manufacture.
Other objects will, in part, be obvious and will, in part, appear hereinafter.
The invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the following detailed description, and the scope of the invention will be indicated in the claims.
Briefly, instead of using an adhesive to secure the two sections of a transformer or choke core to a PWB, the present mounting assembly includes a special three-piece, snap-together clamp assembly that fixates the core sections to the PWB at the appropriate location in exactly the same way from board to board. The clamp assembly includes a generally U-shaped bracket which receives and supports one core section for positioning against one side of the PWB carrying an associated printed winding. The bracket has arms which extend through cut-outs provided in the PWB for the core sections, those arms projecting appreciably beyond the opposite side of the PWB. The second element of the clamp assembly is an annular substrate of resilient material which is positioned against, and may be adhered to, the other core section of the transformer. When that second core section and the substrate are placed against the opposite side of the PWB between the projecting clip arms, the two core sections are automatically aligned with the cut-outs provided therefor in the PWB, and with each other.
The third component of the clamp assembly is a resilient cover member which clips to the projecting ends of the bracket arms and resiliently engages the second core section so that the two core sections are drawn together with their corresponding core faces in abutment while at the same time compressing the resilient substrate so that the substrate biases the first core section against the side of the PWB containing the associated winding.
Thus the clamp assembly increases the reliability of the circuit on the PWB containing the integrated transformer or choke core. It also permits faster through-put in the manufacturing line for such boards and ensures consistent circuit performance from board to board. Still further, the clamp assembly prevents relative movement of the transformer or choke parts due to vibration and rough handling of the PWB, yet allows the core sections to be separated from the board in the event that becomes necessary for purposes of repair or replacement.